1. Technical Field
The present invention relates to a driver circuit for a matrix type display device such as a field emission display or a plasma display.
2. Background Description
Flat panel displays are widely used in a variety of applications, including computer displays. One type of flat panel display device that is well suited for such applications is the thin film field emission display device. Such flat panel displays seek to combine the cathodoluminescent-phosphor technology of cathode ray tubes with integrated circuit technology to obtain thin high resolution displays wherein each pixel is activated by its own electron emitter or set of emitters. Such field emission displays in elementary form include a generally planar substrate having an array of integral projecting emitters which are typically conical projections grouped into emitter sets. Depending upon the size and type of display, a conductive extraction grid is positioned above the emitters and driven at a positive voltage with the emitters selectively activated by providing a current path to ground with appropriate voltage differential between the emitters and extraction grid. The resulting electric field extracts electrons from the emitters. Moreover, the field emission display device additionally includes a display screen-anode formed from a glass plate coated with a transparent conductive material forming a relatively high positive voltage differential with respect to the cathode emitters. The display screen additionally includes a cathodoluminescent layer covering the conductive anode surface whereby emitted electrons are attracted by the anode and strike the phosphor layer to thus cause the emission of light at the impact site which in turn passes through the anode and glass plate. The luminescent level of the produced light is dependent upon the magnitude of the current flow to the emitters that is selectively controlled to produce a desired image.
Existing chips for driving field emission displays provide limited logic functionality and therefore offer only limited display resolution. For example, many conventional driver chips comprise transistors having a 3 micron gate length. Using such transistors, it is difficult to provide much logic functionality, particularly 8-bit logic functionality. One way to improve functionality is to provide additional logic circuits on the driver chips. However, the additional circuits unacceptably increase the size of the driver chips, making driver chips that provide 7- or 8-bit logic functionality impractical.